java--算法--树结构

数的基本介绍：
二叉树的基本介绍：

二叉树的遍历：

package com.model.tree;

/**
 * @Description:测试类
 * @Author: 张紫韩
 * @Crete 2021/7/13 18:54
 * 演示二叉树的遍历
 */
public class TreeDemo01 {
    public static void main(String[] args) {

        Node root = new Node(1, "张紫韩");
        Node node2 = new Node(2, "张紫韩2");
        Node node3 = new Node(3, "张紫韩3");
        Node node4 = new Node(4, "张紫韩4");
        root.setLeft(node2);
        root.setRight(node3);
        root.getRight().setRight(node4);
        BinaryTree tree = new BinaryTree(root);
        tree.perOrder();
        tree.infixOrder();
        tree.postOrder();
//        System.out.println(tree.preFind(node2));

    }
}

class BinaryTree {
    public Node root;

    public BinaryTree(Node root) {
        this.root = root;
    }

    //   遍历这个树
    public void perOrder(){
        if (root!=null){
            root.preOrder();
        }else {
            System.out.println("当前的树为空");
        }
    }
    public void infixOrder(){
        if (root!=null){
            root.infixOrder();
        }else {
            System.out.println("当前的树为空");
        }
    }
    public void postOrder(){
        if (root!=null){
            root.postOrder();
        }else {
            System.out.println("当前的树为空");
        }
    }

    public Node preFind(Node node){
        return root.preFind(node);
    }

}

class Node {
    private int id;
    private String name;
    private Node left;
    private Node right;

    @Override
    public String toString() {
        return "Node{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Node getLeft() {
        return left;
    }

    public void setLeft(Node left) {
        this.left = left;
    }

    public Node getRight() {
        return right;
    }

    public void setRight(Node right) {
        this.right = right;
    }

    public Node() {
    }

    public Node(int id, String name) {
        this.id = id;
        this.name = name;
    }

    //    先序遍历
    public void preOrder() {
        System.out.println(this);
        if (this.left != null) {
            this.left.preOrder();
        }
        if (this.right != null) {
            this.right.preOrder();
        }
    }
    public void infixOrder(){
        if (this.left!=null){
            this.left.infixOrder();
        }
        System.out.println(this);
        if (this.right != null) {
            this.right.preOrder();
        }
    }
    public void postOrder(){
        if (this.left!=null){
            this.left.postOrder();
        }
        if (this.right != null) {
            this.right.postOrder();
        }
        System.out.println(this);
    }

    public Node preFind(Node node){
        if (this.id==node.id){
            return this;
        }
        if (this.left!=null){
            return this.left.preFind(node);
        }
        if (this.right!=null){
            return this.right.preFind(node);
        }
        return null;
    }
}

二叉树的查找：

package com.model.tree;

/**
 * @Description:测试类
 * @Author: 张紫韩
 * @Crete 2021/7/13 18:54
 * 演示二叉树的遍历
 */
public class TreeDemo01 {
    public static void main(String[] args) {

        Node node1 = new Node(1, "张紫韩1");
        Node node2 = new Node(2, "张紫韩2");
        Node node3 = new Node(3, "张紫韩3");
        Node node4 = new Node(4, "张紫韩4");
        Node node5 = new Node(5, "张紫韩5");
        node1.setLeft(node2);
        node1.setRight(node3);
        node3.setRight(node4);
        node3.setLeft(node5);
        BinaryTree tree = new BinaryTree(node1);
//        三种遍历
        tree.perOrder();
        tree.infixOrder();
        tree.postOrder();
//        三种查找
        System.out.println("----------------");
        System.out.println(tree.preFind(4));
        System.out.println("----------------");
        System.out.println(tree.infixFind(4));
        System.out.println("----------------");
        System.out.println(tree.postFind(5));
    }
}

class BinaryTree {
    public Node root;

    public BinaryTree(Node root) {
        this.root = root;
    }

    //   遍历这个树
    public void perOrder() {
        if (root != null) {
            root.preOrder();
        } else {
            System.out.println("当前的树为空");
        }
    }

    public void infixOrder() {
        if (root != null) {
            root.infixOrder();
        } else {
            System.out.println("当前的树为空");
        }
    }

    public void postOrder() {
        if (root != null) {
            root.postOrder();
        } else {
            System.out.println("当前的树为空");
        }
    }

    public Node preFind(int id) {
        if (root != null) {
            return root.preFind(id);
        } else {
            System.out.println("该节点为空");
            return null;
        }
    }

    public Node infixFind(int id) {
        if (root != null) {
            return root.infixFind(id);
        } else {
            System.out.println("该节点为空");
            return null;
        }
    }

    public Node postFind(int id) {
        if (root != null) {
            return root.postFind(id);
        } else {
            System.out.println("该节点为空");
            return null;
        }
    }
}

class Node {
    private int id;
    private String name;
    private Node left;
    private Node right;

    @Override
    public String toString() {
        return "Node{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Node getLeft() {
        return left;
    }

    public void setLeft(Node left) {
        this.left = left;
    }

    public Node getRight() {
        return right;
    }

    public void setRight(Node right) {
        this.right = right;
    }

    public Node() {
    }

    public Node(int id, String name) {
        this.id = id;
        this.name = name;
    }

    //    先序遍历
    public void preOrder() {
        System.out.println(this);
        if (this.left != null) {
            this.left.preOrder();
        }
        if (this.right != null) {
            this.right.preOrder();
        }
    }

    public void infixOrder() {
        if (this.left != null) {
            this.left.infixOrder();
        }
        System.out.println(this);
        if (this.right != null) {
            this.right.preOrder();
        }
    }

    public void postOrder() {
        if (this.left != null) {
            this.left.postOrder();
        }
        if (this.right != null) {
            this.right.postOrder();
        }
        System.out.println(this);
    }

    //    前序查找
    public Node preFind(int id) {
        System.out.println("前序查找进行了比较");
        if (this.id == id) {
            return this;
        }
        Node temp = null;
        if (this.left != null) {
            temp = this.left.preFind(id);
        }
        if (temp != null) {
            return temp;
        }
        if (this.right != null) {
            temp = this.right.preFind(id);
        }
        return temp;
    }

    //    中序查找
    public Node infixFind(int id) {
        Node temp = null;
        if (this.left != null) {
            temp = this.left.infixFind(id);
        }
        if (temp != null) return temp;
        System.out.println("中序查找进行比较了");
        if (this.id == id) {
            return this;
        }
        if (this.right != null) {
            temp = this.right.infixFind(id);
        }
        return temp;

    }

    //    后序查找
    public Node postFind(int id) {
        Node temp = null;
        if (this.left != null) {
            temp = this.left.postFind(id);
        }
        if (temp != null) return temp;
        if (this.right != null) {
            temp = this.right.postFind(id);
        }
        if (temp != null) return temp;
        System.out.println("后序查找进行比较了");
        if (this.id == id) {
            return this;
        }
        return null;
    }
}

二叉树删除节点：

    //    递归删除节点
    public void delNode(int id) {
        if (this.left != null && this.left.id == id) {
            this.left = null;
            return;
        }
        if (this.right != null && this.right.id == id) {
            this.right = null;
            return;
        }
        if (this.left!=null){
            this.left.delNode(id);
        }
        if (this.right!=null){
            this.right.delNode(id);
        }
    }

//    删除节点
    public void delNode(int id){
        if (root==null||root.getId()==id){
            root=null;
        }else {
            root.delNode(id);
        }
    }

  public void delNode01(int id) {
        if (this.left != null && this.left.id == id) {
            if (this.left.left!=null){
                this.left = this.left.left;
            }else if (this.left.left==null&&this.left.right!=null){
                this.left=this.left.right;
            }else{
                this.left=null;
            }

            return;
        }
        if (this.right != null && this.right.id == id) {
            if (this.right.left!=null){
                this.right = this.right.left;
            }else if (this.right.left==null&&this.right.right!=null){
                this.right=this.right.right;
            }else{
                this.right=null;
            }
            return;
        }
        if (this.left!=null){
            this.left.delNode(id);
        }
        if (this.right!=null){
            this.right.delNode(id);
        }
    }

原文地址：https://www.cnblogs.com/zzhAylm/p/15005738.html